This invention relates to a ferroelectric memory (hereinafter sometimes referred to as FeRAM), and more particularly to performance assurance of a ferroelectric memory used in a destructive reading mode.
As a ferroelectric memory, there is known one having a combination of a ferroelectric capacitor and a transistor to form a ferroelectric memory cell that can be electrically rewritable. This type of ferroelectric memory is capable of nonvolatile storage of data by using a hysteresis characteristic of the ferroelectric capacitor. That is, it is similar to EEPROM in capability of holding data even after the power supply is interrupted, and its application to various kinds of IC cards and portable terminals, for example.
With such a ferromagnetic memory, however, unlike EEPROM, data reading is destructive reading. That is, when data is read out, one of “0” and “1” is accompanied by spontaneous polarization reversal, and rewriting is indispensable. This means that stored data is destructed upon interruption of the power supply or a decrease of the voltage below an operation assurance voltage during data reading or other operation.
The conventional ferroelectric memory is not assisted by any operation assurance against accidental interruption of the power supply, for example, during operation.